Flame control for fluid fuel burners



Jan. 18, 1938. w. w. WILLIAMS.

FLAME CONTROL -FOR FLUID FUEL BURNERS Filed March 4, 1936 INVENTOR.

WALTER M'W/LL/4/75 BY M ATTORNEY.

Patented Jan. 18, 1938 um'rao STATES 7 2,105,626 FLAME con'rnor. FORFLUID FUEL BURNER.

Walter W. Williams, Bloomington, 111. Application March 4, 1936, Serial No. 67,020

4 Claims.

This invention relates to improvements in fluid fuel burners, and more particularly to an improved means for controlling the flame at initial ignition in the forced vdraft type of burner.

In the forced draft type of fluid fuel burner mechanism for domestic heating purposes, the full forces of the air and fuel under normal operating pressures are simultaneously delivered, upon initiating operation, and roaring combustion'noise occurs upon initiating ignition of the combustible mixture much greater than the noise of combustion during the operation thereafter.

It is an object of this invention to control the initial delivery of fuel and air in such a manner that the noise of initial combustion-is no greater than during normal operation.

With these and other objects inview, reference is made to the accompanying sheet of drawing which illustrates a preferred embodiment of this invention, with the understanding thatdetail changes may be made without departing from the scope thereof.

In the drawing:

Figure 1 is a view in side elevation of an electrically operated andgcontrolled fluid fuel burner mechanism to which this i vention has been applied, with parts broken a way, and parts shown in section.

Figure 2 is an enlarged detail view in central vertical section of the improved control device, with parts shown in elevation.

Figure 3 is a view partly in elevation and partly in section of a modification of Figure 2. Figure 4 is a schematic wiring diagram of the ignition circuit.

I developeda particular type of .fluid fuelburning mechanism wherein the fuel is delivered in a constant flow by a metering pump to a pressure pump which receives the fiuid fuel and atmospheric air and then delivers the fuel and air under pressure to a chamber wherein the pressure created therein delivers the fuel through a float-controlled valve to a fuel pipe and the air through an air pipe surrounding said fuel pipe to'a nozzle where the fuel and air are delivered in the form of a spray surrounded by air under pressure from a fan blower to be ignited by anelectrical ignition device. This construction is fully disclosed in my prior Patent No. 1,831,277, dated November 10, 1931, and as this invention relates to' a particular control to be added to such structure, it is thought that the above description is sufficient to the understandingof this invention. 2

Figure 1 illustrates an embodiment of this in- 8 and delivers the ing 3 mounting a blower for delivering air under 5 pressure through a draft pipe 4. The blower driving shaft is driven by an electric motor, not shown, and said shaft is extended to operate the rotor 5 of a pressure pump within a housing 6 extending from the blower housing 3 and. a fluid 10 fuel metering pump 1 adapted to deliver fluid fuel to the interior of said pressure pump. The pressure pump is provided with an air intake air received therefrom and the fuel from the metering pump under pressure through pipe 9 to the interior of the closed chamber l formed by the casing ll supported upon the casing I.

The burner nozzle {I2 is mounted concentrically within the draft pipe 4 adjacent its open 20 end and adjacent the electric ignition device l3. The nozzle I2 is connected to the chamber In by an air pipe l4 axially mounted within the draft pipe 4 which enters said chamber adjacent its top. The nozzle chamber I0 by fluid fuel pipe I extending concentrically within said air pipe M which is extended within the chamber 10 to adjacent the bottom thereof, and the entrance of fuel therein I2 is also connected to the is controlled by a. float-operated valve 16 actuated by the level of the fuel within the chamber l0 received from the said pressure pump. The pressure created within the chamber In delivers both fuel through the fuelpipe I5 and air through the air pipe M to the nozzle l2 where 5 the fuel is delivered in a spray into the surrounding stream of air from the blower passing through the draft pipe '4 and the combustion mixture is initially ignited by the ignition device l3. This particular construction above described is fully disclosed in my prior Patent No. 1,831,277,

dated November 10, 1931.

The subject matter of to the particular constru tlon of an air muilier attached to the air intake 8 in the casing 6, of the pressure pump and the results accomplished by such construction.

It is customary in the electricallyoperated and controlled fluid fuel burner mechanism above described, when the space to be' heated has reached the, predetermined degree of temperature for the room thermostat to open the circuit to the burner and the mechanism ceases to operate. The motor, fan blower, fuel mete 'ng pump, and

this invention relates air and fuel pressure pump remain idle until a" call. for heat initiates operation. In accordance with this invention, when operation is initiated,

the air intake to the air and fuel pressure pump is throttled, so that when the said pump first starts to operate, no air is drawn in through the air intake and the suction resulting from continued operation gradually opens the air intake until the-normal amount of air passes therethrough. The result is that at the start of operation the pressure within the chamber In is built up gradually until normal operating pressure is reached and the amount of air and fuel delivered from the chamber III to the nozzle enters the nozzle l2 at a lesser rate and gradually increases to normal as the pressure within the chamber be-' take 8 of the pump casing 6 is provided in the casing |'I adjacent its upper end which is held in alinem'ent with the air intake 8, in any desired manner, such as by screws 2| passed through ears 22 provided upon the casing II to hold said casing securely upon the pump casing. 6.

A dash-pot controlled piston 23 is mounted to reciprocate within the casing H, which, in its lowermost position, will snugly fit therein. A plurality of air intake apertures 24 are arranged about the casing IT below, the under side of the piston 23 when in its lowermost position, as shown in Figure 2. The inner diameter of the casing I1 is gradually increased toward the top from the upper side of the piston 23 when in its lowermost position, anda bleeder passage 25 is provided in the piston 23 in communication with the interior of the casing I! on each side of the piston.-

When the fuel and air pressure pump starts to operate, a suction is created through the ports 8 and 20 within the casing l'l upon the upper side of the piston 23, and the piston, from in its lowermost-position where it obstructs the entry of air through the ports 24, will gradually be drawn upward and in so moving will gradually allow the incoming air to pass'about its periphery as the diameter of the casing increases, until the normal amount of air passesthrough the pump intake 8. If desired, the inner walls of the casing H may 5 be provided with other means for allowing the incoming air to flow in increased volume about the piston as it ascends, such as by providing a plurality of gradually deepening grooves in the walls of the casing.

Inorder to give the piston 23 sumcient weight to normally return to its lowermost position, upon cessation of operation of the fuel and air pressure pump, and to adjustably regulate the rate of upward travel thereof, it' is preferable to mount the piston23 upon a depending concentrictube 26 adapted to engage the 'bOttOm I 8 to-properly locate the piston at the ends of its downward travel, which tube mounts adjacent its lower end a dash-pot 'plungerfl provided with one or more ball checks 28, Sumcient fluid, such-as oil, is in-' troduced into the casing II to co-act with the plunger 21 for the purpose desired.

Upon the upward movement of the piston 23 and plunger 21, the fluid above the plunger passes through ports29 in the tube 26 adjacent the top of said plunger into an axial passage 30 therein, communicating with the interior of the casing l1 below said plunger. It is preferable to provide the said passage 30 with a needle valve 3| adjustably. mounted within the tube 26, as shown in Figure 2. When the pressure pump ceases to operate, the weight of the piston and dash-pot mechanism attached upon the under side thereof will allow the fluid to lift the ball check 28 to accelerate the travel of the plunger.

It is preferable to provide the exterior of the casing l1 with a spaced-apart air strainer 32 in the form of a wire mesh cylinder to prevent foreign matter from entering the air inlet ports 24, and also provide the under side of the piston 23 witha similar cylindrical wire mesh strainer 33 to'prevent the bleeder passage 25 from becoming stopped.

It is desirable to open the circuit to the ignition device after combustion has been completed and this may be accomplished 'by the movement of the piston 23, 23 is to be employed for this purpose, a housing 34 is substituted for the removable cover IS. The housing mounts a tiltable mercury tube switch 35 connected by wires 35 and 35 in the ignition circuit, shown in Figure 4, mounted upon a pivoted support 36 normally passing over the center pf the casing l1 and engaged with a stop 31 within the housing 34 to support the switch in the closed position; The piston 23 is provided upon its upper side with a concentric switch operator 3? adapted, as the piston approaches the upper end of its travel, to engage the support 36 and tilt it about its pivot to open the switch 35. To allow of this operation and still maintain the suction within the casing I 1, it is preferable to employ a flexible metallic bellows 38 having a closed end normally in engagement with the under side of the support 36 when the switch is closed and its open end having an annular flange adapted to be secured between the contacting portions of the top of the casing l1 and housing 34.

It is also preferable to cause the free end of the .40 coiled=aloout the post 39 with its ends engaging the head of said post and upper side of said support to normally insure the returning of the switch 35 to the closed position when the plunger 23 has returned to its lowermost end of travel when the mechanism ceases operation.

As the casing H with its air inlet 20 communieating with the air intake of the air and fuel pressure pump also acts as a muiiier and is provided with the screens 32 and 33 to prevent foreign matter from entering the casing and pump, the interior of the cylindrical air strainer 32 may be provided with a lining of porous felt 4 I, as shown in Figure 2, if desired, to deaden the sound of the air sucked through the screen mesh of the strainer 32.

, What I claim is:

1. In an electrically operated and controlled fluid fuel burning mechanism having an electrical ignition circuit and including a fuel and air pump having an air intake, a cylindrical casing closed at the lower end secured over said intake air inlets provided in the wall of said casing, a piston mounted to. reciprocate between said air inlets and said pump air intake, means in the casing increasing the rate of air flow to said pump air intake as the piston moves in the direction of the said pump air intake,

a housing secured over the open end of the casing, a switch in the ignition circuit mounted within said housing, and means upon the adjacent side of said piston adapted to enter said housing'as the piston approaches that end of its travel to de-energize said ignition circuit.

2. The structure of claim 1, wherein said switch is a mercury tube switch, a tiltable support for said switch pivotally mounted within said housing to extend over the axis of said housing, and said 7 operating means includes an axial projection mounted upon said piston adapted to tilt said support about its pivot.

v3. The structure of claim 1, wherein said switch is a mercury tube switch, a tiltable support for said switch pivotally mounted within said housing to extend over the axis of said housing, and said operating means includes an axial projection mounted upon said piston adapted to tilt said support about its pivot, and wherein a flexible metallic bellows having a closed end and an annular flanged end is secured by its flange between the housing and easing with its closed end engaging the under side of said switch support, whereby the suction is maintained within the easing during operation of the pump.

4. The structure of claim 1, wherein said switch is a mercury tube switch, a tiltable support for said switch pivotally mounted within said housing to extend over the axis of said housing, and said operating means includes an axial projection mounted upon said piston adapted to tilt said support about its pivot, and means within the housing co-acting with the pivoted switch support to contract the said bellows upon the movement of the piston away therefrom.

WALTER W. WILLIAMS. 

